Apple released iOS9 this week for iPhone and iPad, and unlike their previous mobile OS releases this one was accompanied by a soundtrack: the collective woof of expelled air as tens of thousands of Internet advertisers and publishers took a hard punch to the solar plexus. The new mobile OS offers content-blocking and privacy control tools to developers , and - predictably - a day after iOS9 hit the airwaves new ad-blocking apps rocketed to the top of the App Store's charts .